Steam condenser construction

ABSTRACT

An air cooled steam condenser having plates mounted within the condensate outlet header compartment. The plates in effect form a series of subchambers, each of which communicate with a row of cooling tubes in which steam is condensed by a stream of cooling air flowing over, around and past the tubes. The rows of tubes extend transversely of the direction of airflow and the rows extend perpendicular to the direction of airflow at spaced intervals. Tube sleeves extend through a plurality of openings in the outlet header into the header compartment and terminate, each in a separate subchamber. Valves are connected in condensate lines extending from the tube sleeves externally of the header compartment. The valves are adjusted so that the passages through the valves are smaller in area for each successive connected subchamber in the header into which the condensate flows so that only that amount of steam that can be condensed effectively within the tubes in any row, enters such row due to the back pressures created by the varying sizes of valve openings, having regard to the length and the temperature difference at the particular row which determines the cooling effect of the airflow over the successive rows of tubes.

United States Patent [191 Huber [4 1 Feb. 5, 1974 STEAM CONDENSERCONSTRUCTION Ferdinand V. Huber, Canton, Ohio [73] Assignee: EcodyneCorporation, Chicago, Ill.

[22] Filed: Oct. 18, 1971 [21] Appl. No.: 190,087

[75] Inventor:

[52] U.S. C1 165/101, 165/110, 165/122, 165/174, 285/368 [51] Int. Cl.F28b 1/06, F2813 11/00 [58] Field of Search 165/110, 111,174, 101;285/368 [56] References Cited UNITED STATES PATENTS 2,163,591 6/1939Deverall 165/174 X 3,117,620 l/l964 Fuller, Jr 165/101 X 3,262,6857/1966 Pike et al 165/101 X 3,710,854 1/1973 Staub 165/111 1,908,4635/1933 Torrance 165/110 X 3,278,202 10/1966 Smith 285/368 X 1,467,0649/1923 Oleson 285/368 X 1,709,837 4/1929 Bulmahn 285/368 X FOREIGNPATENTS OR APPLICATIONS 1,185,248 3/1970 Great Britain 165/110 PrimaryExaminerAlbert W. Davis, Jr.

6 o io ABSTRACT An air cooled steam condenser having plates mountedwithin the condensate outlet header compartment. The plates in effectform a series of subchambers, each of which communicate with a row ofcooling tubes in which steam is condensed by a stream of cooling airflowing over, around and past the tubes. The rows of tubes extendtransversely of the direction of airflow and the rows extendperpendicular to the direction of airflow at spaced intervals. Tubesleeves extend through a plurality of openings in the outlet header intothe header compartment and terminate, each in a separate subchamber.Valves are connected in condensate lines extending from the tube sleevesexternally of the header compartment. The valves are adjusted so thatthe passages through the valves are smaller in area for each successiveconnected subchamber in the header into which the condensate flows sothat only that amount of steam that can be condensed effectively withinthe tubes in any row, enters such row due to the back pressures createdby the varying sizes of valve openings, having regard to the length andthe temperature difference at the particular row which determines thecooling effect of the airflow over the successive rows of tubes.

8 Claims, 7 Drawing Figures ooooo o PATENTED 3.789.919

' sum 1 or 2 I v INVENTOR. FERDINAND HUBER QW W ATTORNEYS PATENTED 5'9743.789.919

SHEEI 2 OF 2 INVENTOR. FERDINAND V HUBER ATTORNEYS I STEAM CONDENSERCONSTRUCTION CROSS REFERENCE TO RELATED APPLICATIONS The steam condenserconstruction is an improvement upon the constructions shown, describedand claimed in the copending application of Kenneth B. Ris, filed Mar.19, 1971, Ser. No. 126,174, and the copending application of Kenneth B.Ris and myself, filed May 3, 1971, Ser. No. 139,371.

BACKGROUND OF THE INVENTION Field of the Invention The invention relatesto heat exchangers and in particular to air cooled steam condensers.More particularly the invention relates to control means mounted withinthe condenser outlet header and adjusted externally of the headerwhereby the amounts of steam entering various rows of condensing tubesare metered or reduced proportionally to the reduced cooling effect ofthe cooling air due to increased cooling air temperature resulting fromheat extracted from tubes previously cooled, so that only that amount ofsteam that can be cooled efficiently is supplied to the tubes of aparticular row.

Description of the Prior Art Air cooled steam condensers usually includea plurality of condenser tubes arranged in rows one behind the other inthe direction of airflow of the cooling air. Steam enters the condenserinlet header which communicates with the inlet ends of the tubes andthen flows through the tubes wherein it is condensed, Fans blow coolingair across the tubes in an airflow direction generally perpendicular tothe rows of tubes. The steam is condensed by the cooling air to formcondensate as it travels through the tubes, and the condensate iscollected at the outlet ends of the tubes in any suitable manner.Condensation should take place throughout the length of the tubes formost efficient condenser operation.

Problems have arisen in the construction and operation of air cooledsteam condensers as described in US. Pat. No. 3,073,575 relating toinefficient steam feed distribution to the cooling tubes, temperaturedifferential changes due to changingweather conditions, etc. The varioussolutions to such problems suggested in said US Pat. No. 3,073,575,however, are complicated in structure and expensive in execution.

These problems have been eliminated by the constructions shown in saidcopending applications, Ser. Nos. 126,174 and 139,371, wherein fixed andadjustable partition plates are mounted within the condenser inletheader that meter the amounts of steam entering the various rows ofcondensing tubes by forming inlet passages and subchambers.

The adjustable partition plates described in said application, Ser. No.139,371 provide means for selective adjustment of the steam distributionpattern in order to achieve optimum operating conditions at the time ofinitial installation, as Well as to compensate for seasonal changes orfor changes in steam supply factors.

However, adjustment of such plates either requires the condenser to betaken out of operation so that the inlet end coverplate can be removedfor adjustment of the internal partition plates, or else requiresloosening a plurality of lock nuts for manual movement of adjusting rodswhich extend through the end wall and are attached to the partitionplates. Although these adjustment means achieve the intended purpose andsolve the above mentioned problems, they are timeconsuming and mayrequire the condenser to be shut down for adjustment.

The partition plates forming the steam passages of varying widths in thesaid copending applications, are shown located within the condenserinlet header. This results in a steam pressure loss during movement ofthe steam through the inlet header before the steam enters the condensertubes. This reduced pressure results in reduced heat transfer throughthe tubes into the cooling air flow.

Accordingly, it is desirable to provide a condenser construction withsome means for externally selectively adjusting the steam distributionpattern for providing optimum operating conditions in the condenser,preferably in the condenser outlet header, so that adjustments can bemade easily and conveniently without shut down and while the condenseris in operation.

SUMMARY OF THE INVENTION Objectives of the invention include providing asteam condenser construction having adjustable valve means which meterthe amounts of steam flowing through the cooling tubes in tube rows ofthe condenser, proportional to the condensing ability of the tubes inany particular tube row; providing a steam condenser construction inwhich the condenser tubes all have the same length, passage crosssection, number of fins, and total heat exchange surface area; providinga steam condenser construction in which plates forming subchambers aremounted within the condenser outlet header for selective distribution ofsteam; providing a steam condenser construction permitting existingcondenser designs to be converted easily and inexpensively to establishadjustable metered distribution of steam to the several rows of coolingtubes in the condenser; providing a steam condenser construction inwhich the metered distribution of steam may be varied easily andconveniently as condenser design factors vary to insure optimumefficiency in condenser operation; providing a steam condenserconstruction in which the steam flow pattern may be varied by usualvalves mounted externally of the condenser outlet header in thecondensate drain lines, which communicate with the condensate outletsubchambers; providing a steam condenser construction in which the steamflow pattern may be varied easily and conveniently even while thecondenser is in operation; and providing a steam condenser constructionwhich eliminates difficulties heretofore encountered, achieves thestated objectives simply and effectively, and solves problems andsatisfy existing needs.

These objectives and advantages are obtained by the steam condenserconstruction the general nature of which may be stated as including aplurality of tubes arranged in a plurality of generally parallel rows,extending between and communicating with a steam inlet header and acondensate outlet header; the rows of tubes extending transversely ofand at spaced intervals perpendicular to the direction of airflow ofcooling air that passes over and around the rows of tubes to condensesteam flowing through the tubes from the inlet to the outlet header; thecondensate outlet header having a chamber and partition means mountedwithin the chamber dividing the chamber into a plurality of subchambers;the subchambers communicating with at least one row of tubes; separatecondensate drain means communicating with each of the subchambers andextending externally from the outlet header chamber; valve meansconnected with each drain means; control means for the valve meanslocated externally of the outlet header chamber whereby the valve meansmay be individually adjusted by the control means to create backpressures in the corresponding rows of tubes to regulate the flow ofinlet steam in successively smaller amounts to each successive row ofsaid tubes corresponding to the reduced cooling effect of the airflow ofcooling air passing successively over the spaced rows, so that the steamflow in each row of tubes may be maintained at an optimum operatinglevel by such adjustment to compensate for changes in operatingconditions; and the partition means including a plurality of platesmounted on and extending between the outlet header tubesheet and sidewall.

BRIEF DESCRIPTION'OF THE DRAWINGS Preferred embodiments of the inventionillustrative of the best modes in which applicant has contmeplatedapplying the principles are set forth in the following description andshown in the drawings and are particularly and distinctly pointed outand set forth in the appended claims.

FIG. 1 is a perspective view, with portions broken away, showing an aircooled steam condenser equipped with the improved steam control system;

FIG. 2 is a diagrammatic front elevation of the steam condenser shown inFIG. 1;

FIG. 3 is an enlarged fragmentary top plan view, with portions brokenaway and in section, looking in the direction of arrows 3-3, FIG. 2 andshowing one condenser section;

FIG. 4 is a sectional view taken on line 4-4, FIG. 3;

FIG. 5 is an enlarged sectional view taken on line 5-5, FIG. 4;

FIG. 6 is a further enlarged fragmentary sectional view taken on line6-6, FIG. 5; and

FIG. 7 is a reduced fragmentary sectional view similar to FIG. 5 showinga modified steam condenser construction. Similar numerals refer tosimilar parts throughout the drawings.

DESCRIPTION OF PREFERRED EMBODIMENTS First Embodiment I A typical aircooled heat exchanger is indicated at 1, (FIGS. 1 and 2) and includestwo steam condenser sections 2 and 3 supported on frame members 4 andhaving side and end panels 5 mounted on the frame members 4. Fans 6mounted on pedestals 7 beneath condenser sections 2 and 3 blow coolingair (indicated by arrows A, FIG. 2) upward through sections 2 and 3.

Steam inlet pipes 8 communicate with a source of steam, such as theexhaust of a steam turbine, to be condensed. and form steam inlets forthe individual sections 2 and 3. Condensate outlet lines 9 are connectedto the opposite ends of sections 2 and 3 and de- Therefore only onecondenser section 2 (FIGS. 3-6) is described in detail.

Condenser section 2 includes a plurality of cooling tubes 11 preferablyhaving helical fins 12 extending outward therefrom. Tubes 11 are mountedwithin a frame 13 having side channels 14, an inlet header 15 and anoutlet header 16.

Tubes 11 are mounted parallel to each other within frame 13 in aplurality of rows 17, 18, 19 and 20 spaced one above the other (FIGS. 4,5 and 6) arranged in order along the direction of air flow indicated bythe arrow A. Tubes 11 in a particular row may be spaced intermediate thetubes in the adjacent rows, above and below, as shown in FIG. 5.Likewise, tubes 11 are assembled within frame 13 so as to have a slightincline from inlet header 15 to outlet header 16 so that condensateflows or drains into header 16.

Outlet header 16 may have a welded construction as shown in U.S. Pat.No. 3,582,599 of Melvin Yohn. Such construction may include a generallyrectangular cross-section formed by top and bottom walls 21 and 22,tubesheet 23, side wall 24, and end walls 25. The outlet ends of tubes11 are connected in a usual manner by expanding or welding in tubesheet23; and holes 26 in wall 24 aligned with tubes 11 permit access intoheader 16 and tubes 11 for cleaning and for removing any obstructionsthat may form in tubes 11.

Steam inlet header 15 (FIGS. 3 and 4) may be constructed similar toheader 16 having aligned holes 27 and 28 formed in tubesheet 29 and sidewall 30 for connection with the inlet ends of tubes 11 and insertion ofremovable plugs 31, respectively. Steam inlet opening 32 in top wall 33of header 15 is connected by flange coupling 34 with coupling 35 onsteam inlet line 8.

In accordance with the invention a plurality of partition plates 36, 37and 38 are mounted within header 16 between tubesheet 23 and side wall24 by welds 39. The plates 36, 37 and.38 preferably are parallel to eachother and to bottom wall 22, and are mounted between tube rows 17 and18, 18 and 19, 19 and 20, respectively. Thus, subchambers 40, 41, 42 and43 are formed within header l6.

Tube sleeves 45, 46 and 47 extend through a plurality of spaced openings48 in bottom wall 22 into the compartment of header l6 and communicatewith subchambers 41, 42 and 43, respectively, as shown in FIG. 5. Notube sleeve is required for communication with subchamber 40 since itsrespective outlet line 9 can communicate directly through an opening 48with subchamber 40.

Tube sleeve 45 extends through subchamber 40 and terminates in anopening 49 in plate 36; tube sleeve 46 extends through subchamber 40,through an opening 50 formed in plate 36, through subchamber 41 andterminates in an opening 51 formed in plate 37; and tube sleeve 47extends through subchamber 40, through a third opening 52 formed inplate 36, through subchamber 41, through a second opening 53 formed inplate 37, through subchamber 42 and terminates in an opening 54 formedin plate 38.

Tube sleeves 45-47 preferably are removably mounted in outlet header 16to enable access through side wall holes 26 to those tubes 11, shown indashed lines, FIG. 5, located behind the tube sleeves for removing anyobstructions that may form in these tubes. Therefore, a slidable fit isprovided between the tube sleeves and bottom wall 22 and plates 36-38 atopenings 48 and the various plate openings through which sleeves 45-47extend. Sleeves 4547 may be held in position by clamping an outwardlyextending annular flange 55 (FIG. 6) formed at the lower end of eachtube sleeve between a pair of usual couplings 56 and 57.

Flange couplings 56 surround bottom wall openings 48 and may be weldedat 58 to header bottom wall 22. Couplings 57 are welded at 59 to theends of condensate outlet lines 9 and may be clamped to couplings 56 bybolts 60. A pair of gaskets 61 preferably is placed between thosecouplings 56 and 57 which clamp a tube sleeve annular flange 55therebetween, and the respective tube sleeve flange 55 to provide an airand liquid tight connection.

Thus, tube sleeves 45-47 may be removed easily by unclamping couplings56 and 57 by removal of bolts 60, and then freely sliding the tubesleeve from within header 16 through bottom wall opening 48.

The small amount of condensate and uncondensed steam that may leakbetween the subchambers through the slidable fit openings between thesleeves and partition plates is insignificant and does not affect thecondenser operation.

The adjustment means for varying the amounts of steam entering tube rows17-20 is provided by valves 62, 63, 64 and 65 which are installed in thecondensate lines 9 communicating with subchambers 40, 41, 42 and 43,respectively.

Valves 6265 are of a usual construction such as a gate or butterflyvalve, and are placed in each condensate line 9 between condensate drainopenings 48 and main condensate drain line 10. Valves 6265 in accordancewith the invention are located externally of header 16 and are readilyaccessible for regulation of their internal valve opening, as by simplemovement of control crank valve wheels 66.

Steam flow, indicated by arrow B (FIG. 4), enters header throughdistribution pipe 8 and inlet opening 32. The amounts of steam B,, B Band B that enter tube rows 17, 18, 19 and 20, respectively, areindividually controlled and regulated by valves 62, 63, 64 and 65,respectively, and crank wheels 66. In effect four individual andseparate steam and condensate paths are formed in condenser section 2.Each path consists of a row of cooling tubes, a condensate subchamber, acondensate outlet line and a control valve.

Back pressure is created in each of the individual paths by valves62-65, the amounts of which depend upon the size of valve openingsregulated by crank wheels 66. The smaller the valve opening, the greaterwill be the back pressure, and correspondingly smaller will be theamount of steam entering the particular row of tubes which communicateswith the respective subchamber and connected valve.

Valves 62-65 are adjusted so that the valve 62 has the largest opening,valve 63 the next largest opening, valve 64 the third largest openingand valve 65 the smallest opening. Therefore, a larger amount of steamB, enters the tubes in row 17 for condensation therein than the reducedamount of steam B entering tube row 18 and likewise the further reducedamounts of steam B and B, entering tube rows 19 and 20. This continualreduction in amounts of steam entering succeeding tube rows of similartubes spaced along the direction of flow A of the cooling air,compensates for the continual increase in temperature of the cooling airand the decreasing mean effective temperature difference as the airpasses from row 17 over the subsequent rows 18-20 picking up heat fromthe previously cooled rows of tubes.

The sizes of the valve openings are determined by ad- 5 justing valvewheels 66 in any particular installation,

taking into consideration factors including the pressure and temperatureof the steam entering header 15, the velocity and temperature of coolingair flowing at A past the tubes 11, and the total finned heat exchangecooling surface of tubes 11. Ideally, the sizes of the valve openingswill be such that the amounts of steam B B entering the respective rows17-20 of tubes 11 will be completely condensed as steam flow in any tube11 reaches the outlet header 16. In actual operation the mixtureentering outlet header 16 may consist of percent condensate andapproximately 10 percent steam.

Thus, in the event that any of these above design factors change, valvewheels 66 may be adjusted accordingly to admit more or less steam B Bthrough tube rows 17-20 for condensation within tubes 11. For examplethe sizes of the valve openings may be increased in winter months incold weather regions due to the increased cooling ability of the coolingair. Likewise, should the pressure or temperature of the steam enteringheader 15 change due to a change in operating conditions of the sourceof steam supply, the valve openings may be adjusted accordingly toenable maximum efficiency to be achieved in the operation of thecondenser.

Thus, any individual row of tubes receives only that amount of steamthat can be condensed throughout its length, eliminating premature orinsufficient condensation within the tubes, while using tubes allidentically the same in the construction of the condenser. The valvemeans may be adjusted easily and conveniently permitting more or lessamounts of steam to flow into the various tube rows, so that as thefactors which effect the condensation rate within the tubes change, thesupply of steam to the tubes can be changed to enable the condenser tooperate at optimum efficiency.

The improved external adjustment and control means for individuallyvarying the amounts of steam to the tube rows permits ease ofadjustability heretofore unattainable. Such ease in adjustment enablesthe steam flow pattern to be changed continually to match any change inthose factors which affect the rate of condensatiion.

This constitutes an important improvement over the adjustable partitionplates of said copending application, Ser. No. 139,371 which eitherrequires shutting down the condenser for removal of the headercoverplate for manual adjustment of internal partition plates, or elserequires the movement of the internal partition plates by means ofexternally extending adjustment rods. Either means of adjustmentrequired a considerable amount of time in comparison with the simplemovement of valve crank wheels 66 of valves 62-65.

Valve 62 which is located in the drain line 9 which communicates withsubchamber 40 may be eliminated in many condenser installations. Suchelimination is possible since tube row 17 which communicates withsubchamber 40 is cooled first by the air flow, before the air flowtemperature is increased by heat transfer from flowing past subsequenttube rows and can be more uniformly controlled.

Thus, the openings in valves 63, 64 and 65 can be varied so as to enablethe proper amounts of steam to flow through tube rows l8, l9 and withthe remaining amounts flowing through rows 17. in those installationswhere valve 62 .is eliminated, the size of condensate line 9communicating with subchamber 40 must be predetermined by propercalculations based upon the average value of the factors effecting thecondensation rate and the adjustability provided by valves 63-65. SecondEmbodiment A modified construction of the improved steam condenserconstruction is shown in FIG. 7 in which only a single partition plate67 is mounted within the condensate outlet header 68 dividing it intosubchambers 69 and 70.

Each subchamber communicates with two rows of cooling tubes instead ofone, as in condenser section 2 where a single row of tubes communicateswith each subchamber.

The header bottom wall 71 is formed with two spaced openings 72 and 73.A tube sleeve 74, similar to tube sleeve 45-47, extends through opening73 and subchamber 69, and communicates with subchamber 70 through anopening 75 formed in plate 67.

Control valves (not shown) are placed in the two condensate drain lines9 in a manner similar to valves 62-65 for varying the amounts of steamentering the tube rows.

IN GENERAL Accordingly, the improved steam condenser constructionprovides for progressively reducing the amount of steam passing throughthe rows of tubes in the path of flow of cooling air; enables condensertubes having the same length, the same passage cross section, the samenumber of tins and the same total heat exchange surface to be used infabricating the condenser; enables many designs of steam condensers tobe easily and inexpensively converted to the improved steam condenserconstruction; enables the amounts of steam that enter the various rowsof tubes to be adjusted easily and conveniently, externally of thecondenser so that if those factors which affect the rate of condensationare changed, then the amounts of steam to be condensed may be adjustedaccordingly to provide maximum efficiency in the operation of thecondenser; prevents premature condensation which may result in frozenconditions during cold weather; provides a means of adjusting the steamflow to the various rows of tubes without requiring the condenser to beout of operation; and provides such a construction which is effective,safe, inexpensive, and efficient in assembly, operation and use, andwhich achieves all the enumerated objectives, provides for eliminatingdifficulties encountered with prior devices, and solves problems andobtains new results in the art.

In the foregoing description, certain terms have been used for brevity,clearness and understanding but no unnecessary limitations are to beimplied therefrom beyond the requirements of the prior art, because suchterms are used for descriptive purposes and are intended to be broadlyconstrued.

Moreover, the description and illustration of the invention is by way ofexample, and the scope of the invention is not limited to the exactdetails of the construction shown or described.

Having now described the features, discoveries and principles of theinvention, the manner in which the improved steam condenser constructionis constructed, assembled and operated, the characteristics of the newconstruction, and the advantageous, new and useful structures, devices,elements, arrangements, parts, and combinations are set forth in theappended claims.

I claim:

1. In a steam condenser ofa type in which a plurality of tubes arearranged in a plurality of generally parallel rows, extending betweenand communicating with a steam inlet header and a condensate outletheader; in which the rows of tubes extend transversely of and at spacedintervals perpendicular to the direction of airflow of cooling air thatpasses over and around the rows of tubes to condense steam flowingthrough the tubes from the inlet header to the outlet header; and inwhich all of the tubes in all of the rows have the same internaldiameter and length and the same heat exchange cooling surface area; thecondensate outlet header having partition means mounted within theheader dividing the header into a plurality of subchambers; thesubchambers each communicating with at least one row of tubes; separatecondensate drain means for and communicating with each of saidsubchambers and extending externally from the outlet header; a pluralityof the drain means including valve means; and the valve means eachincluding control means located externally of the outlet header beindividually adjusting the flow therethrough so as to create backpressures in the corresponding rows of tubes and thereby regulate theflow of inlet steam in successively smaller amounts to each successiverow of said tubes corresponding to the reduced cooling capacity of theairflow of cooling air passing successively over the spaced rows so thatthe steam flow in each row of tubes may be maintained at an optimumoperating level by such adjustment to compensate for changes inoperating conditions.

2. The construction defined in claim 1 in which the outlet headerincludes a tubesheet and side wall; in which the partition meansincludes a plurality of partition plates; and in which the partitionplates are mounted on and extend between said tubesheet and side wall.

3. The construction defined in claim 2 in which the outlet headerincludes a bottom wall; in which said bottom wall is formed with aplurality of openings; in which the partition plates are each formedwith at least one opening, in which the partition plate openings arealigned with said bottom wall openings; in which a plurality of thedrain means includes tube sleeves; and in which said tube sleeves extendthrough the aligned bottom wall and partition plate openings forcommunication with the outlet header subchambers.

4. The construction defined in claim 3 in which the tube sleeves areremovably mounted on the outlet header.

5. The construction defined in claim 3 in which the tube sleeves haveslidable fits between the header bottom wall and partition plates at thetube sleeves extensions through the openings formed in said bottom walland partition plates.

6. The construction defined in claim 3 in which a plurality of flangecouplings are mounted on the outlet header bottom wall; in which each ofthe bottom wall openings is surrounded by one of said couplings; and in8. The construction defined in claim 1 in which the drain means includesa plurality of tube sleeves; in which the tube sleeves each communicatewith a separate subchamber and extend externally from the outlet header;in which a drain line is detachably connected to and extends from theexternal end of each tube sleeve; and in which the valve means and valvecontrol means are connected with said drain lines.

1. In a steam condenser of a type in which a plurality of tubes arearranged in a plurality of generally parallel rows, extending betweenand communicating with a steam inlet header and a condensate outletheader; in which the rows of tubes extend transversely of and at spacedintervals perpendicular to the direction of airflow of cooling air thatpasses over and around the rows of tubes to condense steam flowingthrough the tubes from the inlet header to the outlet header; and inwhich all of the tubes in all of the rows have the same internaldiameter and length and the same heat exchange cooling surface area; thecondensate outlet header having partition means mounted within theheader dividing the header into a plurality of subchambers; thesubchambers each communicating with at least one row of tubes; separatecondensate drain means for and communicating with each of saidsubchambers and extending externally from the outlet header; a pluralityof the drain means including valve means; and the valve means eachincluding control means located externally of the outlet header beindividually adjusting the flow therethrough so as to create backpressures in the corresponding rows of tubes and thereby regulate theflow of inlet steam in successively smaller amounts to each successiverow of said tubes corresponding to the reduced cooling capacity of theairflow of cooling air passing successively over the spaced rows so thatthe steam flow in each row of tubes may be maintained at an optimumoperating level by such adjustment to compensate for changes inoperating conditions.
 2. The construction defined in claim 1 in whichthe outlet header includes a tubesheet and side wall; in which thepartition means includes a plurality of partition plates; and in whichthe partition plates are mounted on and extend between said tubesheetand side wall.
 3. The construction defined in claim 2 in which theoutlet header includes a bottom wall; in which said bottom wall isformed with a plurality of openings; in which the partition plates areeach formed with at least one opening, in which the partition plateopenings are aligned with said bottom wall openings; in which aplurality of the drain means includes tube sleeves; and in which saidtube sleeves extend through the aligned bottom wall and partition plateopenings for communication with the outlet header subchambers.
 4. Theconstruction defined in claim 3 in which the tube sleeves are reMovablymounted on the outlet header.
 5. The construction defined in claim 3 inwhich the tube sleeves have slidable fits between the header bottom walland partition plates at the tube sleeves extensions through the openingsformed in said bottom wall and partition plates.
 6. The constructiondefined in claim 3 in which a plurality of flange couplings are mountedon the outlet header bottom wall; in which each of the bottom wallopenings is surrounded by one of said couplings; and in which the tubesleeves slidably extend through said couplings into the outlet header.7. The construction defined in claim 6 in which each tube sleeve isformed with an outwardly extending annular flange on the tube sleeve endexternal of the outlet header; in which the drain means each includes adrain line having a coupling attached on one end of said drain line; andin which said sleeves annular flanges are clamped between said drainline couplings and the header bottom wall couplings.
 8. The constructiondefined in claim 1 in which the drain means includes a plurality of tubesleeves; in which the tube sleeves each communicate with a separatesubchamber and extend externally from the outlet header; in which adrain line is detachably connected to and extends from the external endof each tube sleeve; and in which the valve means and valve controlmeans are connected with said drain lines.